Electromagnets are typically used in rotating machinery applications as replacements for the widely used friction bearings or roller element bearings. The use of a magnetic field effectively suspends the rotating shaft of the considered machinery, allowing contactless bearing operation. The resulting magnetic bearing operates without requiring any lubricating agent and at extremely reduced friction losses. Advanced power electronics are required in order to maintain the concentricity between the shaft and the supporting bearing as well as to prevent unwanted shaft vibrations. Further reading regarding the different types of magnetic bearings may be found in “Magnetic Bearings—Theory, Design, and Application to Rotating Machinery,” Schweitzer G., Maslen E. (editors), Springer-Verlag, 2009, ISBN 978-3-642-00496-4.
However, the crankshaft of an internal combustion engine experiences a different type of loading compared to the rotating shaft of rotating machinery such as a turbines. Due to the reciprocating piston motion and applied gas pressure, the load which has to be supported by the main bearings is periodic and is characterized by short pulses, which may be further discussed in “Diesel Engine Transient Operation: Principles of Operation and Simulation Analysis” Rakopoulos, C. D., Giakoumis, E. G., Springer, first edition (Mar. 26, 2009), ISBN 1848823746. As a result, the application of magnetic bearings as described by Schweitzer is not practical for many reasons, including magnetic bearing sizing as well as control concerns.